It is a common practice to deliver fluids such as medications to a patient intravenously by means of a pumping device, such as a peristaltic pump. Such pumps are useful because they can deliver the medication in a highly controlled and precise fashion, and because they do so without coming in contact with the medication. The fluid is moved through a flexible IV tube by pressing a pumping member against the tube sufficiently to move the fluid in the tube downstream towards the patient. In the case of peristaltic mechanisms having multiple pumping fingers, the fingers are moved against the tube in a sequential manner from upstream to downstream to sequentially occlude the tube thereby moving the fluid in the tube downstream towards the patient. When the IV tube is mounted correctly in the pump, the IV tube is at all times occluded by one of the pumping members, thereby preventing the “free flow” of fluid to the patient. “Free flow” of medical fluids is undesirable since the flow of the fluid is uncontrolled and the prescribed treatment is not followed.
It is common for the peristaltic pumping mechanism to be located in a housing with a hinged door. The tube through which the fluid is to be moved is placed in contact with the pumping mechanism inside the door, with the ends of the tubing typically extending out the top and bottom of the door opening. As the door is shut over the tube, a platen on the inside of the door presses against the IV tube to provide a backing surface against which the pumping members can occlude the tube. The platen is typically spring loaded, although not always, against the pumping mechanism so that one or more of the pumping fingers of the pumping mechanism occludes the tube once the door is shut over the tube. This then prevents free flow while the door is shut.
This arrangement of the W tube relative to the pumping mechanism requires that there be some means for preventing flow in the tube when the door of the pump is open. Merely opening the pump door would relieve the tube from the occluding pumping mechanism/platen combination and free flow could possibly occur. This could result in the uncontrolled infusion of medication into the patient under the influence of the static head pressure in the tube, or blood from the patient could flow back into the IV tube. Known devices for preventing the unwanted flow in the tube include manual clamps on the tube separate from the infusion pump, and automatic occluding devices mounted on the pump. The manual devices require some manipulation skill on the part of the attending technician, and there is always the chance that the technician will forget to properly time the manual clamping process of the tube before the door of the pump is opened. Furthermore, the door may be accidentally opened, resulting in free flow in the tube.
Automatic devices mounted on the infusion pump for assisting in clamping and unclamping infusion tubes have improved. In particular, the reliability in timing the occlusion and release (unocclusion) of the tube with the disengagement and engagement, respectively, of tube with the pumping members has improved. Typically, the action of opening the door is relied upon to initiate the occlusion of the IV tube by a clamp, and the action of closing the door is relied upon to initiate the release or unocclusion of the tube by an IV tube clamp. However, there still can occur the possibility of an inadvertent free flow of fluid through the IV tube due to operator error in regard to use of such devices.
Additionally, medical instruments having such automatic devices typically have clamp detectors to sense the correct operation of the clamp. The detector or detectors may be used to determine if the clamp is in the unoccluded position or occluded position. The processor of the medical instrument monitors the detector or detectors and may be programmed to advise the operator accordingly. For example, the processor may monitor the flow clamp detector to determine if the detector indicates that the clamp is in the unoccluded position. The processor may also monitor other detectors of the instrument, such as a door open detector of an infusion pump. As the processor receives various detector signals, or pump configuration signals, and if it determines from those detectors or from other information that indicates the configuration of the pump that the flow clamp should be in the occluded position for this configuration, the processor may provide an alarm if the clamp detector indicates that the clamp is in the unoccluded position. If such alarms are based on clamp detector information that is not accurate, they can become a nuisance to the nursing staff. Therefore, accurate clamp position or configuration detection systems are desired.
Hence, those skilled in the art have identified a continuing need to provide an improved apparatus that will automatically and positively occlude an IV tube before the occluding pumping mechanism is disengaged from the tube. A further need has been recognized for an apparatus that will automatically and positively maintain the IV tube in an occluded state until after the occluding pumping mechanism is engaged with the tube. A still further need has been recognized for an apparatus that will reliably occlude the IV tube, that is inexpensive to manufacture, and is easy to use. Yet a further need has been recognized for an apparatus that can be manually operated between occluding and nonoccluding configurations. In addition, a need has been recognized for an apparatus for which occlusion of a flow clamp is reliably detected by a sensor associated with pumping device. The present invention fulfills these needs and others.